1. Field of the Invention
The present invention relates to a light reflecting material, a package for a light emitting element accommodation, light emitting device and a method of manufacturing package for a light emitting element accommodation.
2. Related Art
In the past, a package having a substrate of ceramic has been used as a light emitting element package for storing a light element of a light emitting diode (LED), a semiconductor laser diode (LD) etc.
A conventional package having a substrate of ceramic comprises a substrate mounting a light emitting element and a frame body which is provided on the substrate and has a penetration hole. A power supply conductor for flowing current through the emitting element from the outside is provided at the substrate, this power supply conductor and the emitting element are connected by a bonding wire electrically. Then, the emitting element which is supplied with current from the outside through the power supply conductor, the bonding wire etc. emits light and the light emitted from the emitting element radiates to the outside directly or to the outside after reflected by an round inner surface of the penetration hole of the frame body. Thus, a shape and a composition of the round inner surface of the penetration hole of the frame body greatly influence an emitting efficiency of the emitting device mounting the emitting element.
Metals which have a relatively high reflectance are known as materials for the light reflection for the frame body of this kind of the emitting device. Material of ceramic etc. which is adjusted in the thermal expansion coefficient to the substrate and is plated with the metal is also known as the other material for reflecting (for example, see the patent document 1). Ag is known as the plating material having a relatively high reflectance, in the case of using Ag as the plating material although the reflectance is about 90% of the barium sulfate at the light of the wavelength of about 460 nm, the reflectance is low at the light of the wavelength of not more than about 460 nm and the reflectance is 77% at the average of the range from 250 nm to 800 nm.
Furthermore, the package for the light emitting element accommodation consists of the alumina which forming the reflecting wall surrounding the light emitting element and be integrated with the substrate is also proposed. This light reflecting material consists of alumina whose average particle diameter after sintering is 4 μm.    Patent Document 1: JP-A-2004-228531
However, if using the metal as the light reflecting material and connecting it to a substrate like ceramic which has a different thermal expansion coefficient, a bend of the substrate and an exfoliation of the frame body are occurred because their thermal expansion coefficients are not fitting.
If using the frame body whose base material is ceramic like Patent Document 1, the bend of the substructure and the exfoliation of the frame body are controlled. However, the improvement of the light reflectance is limited even if it is plated with the metal, and the manufacturing cost increases because the process of plating generates.
Furthermore, said sintered alumina can not get a sufficient reflectance and the reflectance is less than the metal plating using Ag at a predetermined wavelength region.
The present invention has been made in view of the above matter, and has its object to provide a light reflecting material, a package for a light emitting element accommodation, a light emitting device and a method of manufacturing a package for a light emitting element accommodation which increases a reflectance without plating metal onto ceramic.